1. Field of the Invention
This invention relates to a method of limiting and localizing the penetration of drilling fluid into porous underground strata, crevices and fissures during the drilling of wells.
2. Description of the Prior Art
In the well drilling industry, it is desirable and often necessary to insure that the walls of the bore hole are impermeable. This necessity arises since it is customary to provide a well drilling fluid which is passed downward through the drill string and upward externally of the drill string in order to cool, lubricate and carry away the cuttings produced by the drill bit. This drilling fluid has desirable properties which are interfered with by the loss of a liquid portion of the fluid through openings in the well wall.
Various methods for depositing material in openings in the bore hole wall to reduce or prevent lost circulation have been invented. U.S. Pat. No. 1,807,082 issued May 26, 1931 to Boynton discusses the introduction of mica flakes into the well fluid circulation for coating the wall of the well hole. U.S. Pat. No. 2,342,588 issued Feb. 22, 1944 to Larkin discloses the method of mixing a quantity of small pieces of sponge rubber with the well drilling fluid. The sponge rubber particles are deposited in the cracks and fissures and thereafter expand to fill them. U.S. Pat. No. 2,353,372 issued July 11, 1944 to Stone discloses the mixing of fragmented organic grainless foil with the well drilling fluid for circulation therewith and disposition within the cracks and fissures of the bore hole walls for reducing the lost circulation of the well drilling fluid. U.S. Pat. No. 2,634,236 discloses the admixing of fiberized leather with the drilling fluid. U.S. Pat. No. 3,221,825 issued Dec. 7, 1965 to Henderson discloses the mixing of cork particles with the well drilling fluid for sealing off the cracks and fissures of the well hole walls. U.S. Pat. No. 3,254,064 issued May 31, 1966 to Nevins discloses the use of solid, stretchable, deformable organic polymers in the well drilling fluid for blocking off leaks in the well hole walls. U.S. Pat. No. 3,568,782 issued Mar. 9, 1971 to Cox discloses the use of popcorn in the well drilling fluid. U.S. Pat. No. 3,788,405 issued Jan. 29, 1974 to Taylor discloses the use of a mixture of straw and chemical wood pulp fibers for blocking off the lost circulation in the well bore.